Difference between ASME B16.47 Series A and Series B Flanges

ASME B16.47 Series A flanges are thicker, heavier, and stronger, while Series B flanges are lighter with smaller bolt holes. As such, engineers and contractors use Series A flanges in heavy-duty applications and Series B flanges in pipeline connections.

When it comes to ASME B16.47 flanges, Series A and Series B might look similar at first glance… but the differences run deep.

Series A flanges are the heavyweights—thicker and stronger, ideal for connections involving valves and equipment. Series B, in contrast, is the lighter option, with smaller bolt holes and a design suited for pipeline connections where reduced weight matters.

Understanding these distinctions can help you choose the best ASME flange for your project’s needs. Read on to see how each type excels in its own way.

Quick Comparison

ASME B16.47 Series A and Series B Flanges Head-to-Head

Physical and Dimensional Attributes 

ASME B16.47 Series A and Series B flanges each bring their own set of physical traits and dimensions to the table.

Series A flanges are thicker and heavier, a characteristic that makes them perfect for high-stress applications where durability is essential. That’s why you’ll find them in environments demanding robust connections, such as in heavy machinery or high-pressure systems.

Series B flanges, on the other hand, are designed to be lighter and more compact. These flanges excel in scenarios where weight savings and ease of installation are priorities. You’ll see Series B flanges in applications like indoor pipelines or in projects that require simple, straightforward connections without the extra bulk.

Common Applications 

ASME B16.47 Series A flanges are the ones you call in when things get intense. They’re built for industries that need strength you can rely on, day in and day out. Series A flanges are ideal for:

• Equipment connections in high-stress environments, where stability is essential to withstand intense operating conditions.
• High-pressure valve installations that need strong, reliable holds to maintain system integrity under variable pressures.
• Industrial machinery connections, especially in settings where frequent pressure shifts demand durable flanges.
• Outdoor setups exposed to fluctuating temperatures and pressures, where the thickness of Series A flanges ensures longevity.

ASME B16.47 Series B flanges offer a lighter, compact option for streamlined applications. They’re ideal for scenarios where reduced weight and efficient handling are beneficial, such as:

• Pipeline connections in long stretches, where Series B’s lighter weight minimizes stress on the pipeline structure.
• Indoor pipelines that don’t require the same level of durability, but benefit from a more compact flange design.
• Compact installations where easy handling and space-saving are priorities, making Series B a practical choice for tight spaces.
• Standard pipe-to-pipe connections in projects that need reliable yet economical flanges.

Both Series A and Series B flanges adhere to ASME B16 standards, with additional references like ASME B16.4, ASME B16.42, and ASME B16.39 providing guidelines for different applications, sizes, and pressure ratings across various flange types.

Manufacturing Standards

Manufacturing standards tend to differ between  ASME B16.47 Series A and Series B Flanges.

Series A flanges follow the MSS SP44 standard, which prioritizes strength and durability over other things. No surprise they’re built thicker and heavier, with larger bolt holes ready to tackle the toughest conditions

Series B flanges adhere to API 605—a standard that focuses on efficiency and lighter-weight construction. With smaller bolt holes and more bolts overall, they spread the load evenly while keeping things manageable on the scale.

Size and Pressure Ratings 

The size and pressure ratings of ASME B16.47 Series A and Series B flanges differ to meet varying project demands.

Series A flanges, with their robust build, support higher pressure classes across larger sizes. 

Series B flanges, on the other hand, offer a lighter option with slightly reduced size limits at the higher pressure classes.

Size and pressure rating at a glance:

Use these specifications to select the appropriate flange based on the pressure and size requirements of your project.

Types and Material Options 

ASME B16.47 Series A and Series B flanges come in two main types: weld neck and blind flanges.

• Weld neck flanges are the strong ones. They weld right onto the pipe, making them perfect for handling high pressure without any fuss. If you need a solid, steady connection, Weld Neck is your pick.
• Blind flanges act like a cap for the pipe. They seal off the end, which is handy if you need to inspect or maintain the system down the line.

As for materials, you can choose from a few options for your specific flange:

So, whether you’re after pure strength, corrosion resistance, or a balance of both, there’s a type and material to fit your project.

Customization Options

ASME B16.47 Series A and Series B flanges aren’t one-size-fits-all. For projects with unique specifications, custom options allow engineers to get exactly what they need.

For example, you may need a specific inside or outside diameter, an adjusted thickness, or a unique bolting arrangement. With the right customization options, you can achieve the precise fit and performance your project requires—and then some.

Getting Your ASME B16.47 Series A and Series B Flanges

At Long’an Flange, our manufacturing capabilities ensure precision and quality at every step. We operate over 100 CNC lathes and advanced machining centers, and our fully equipped lab is dedicated to quality assurance. Here’s what we offer to meet your customization needs:

With options like slip-on, weld neck, blind flanges, and custom designs, we deliver flanges tailored to fit your project perfectly.

Contact us today for a quote or more information on how Long’an Flange can help bring your project to life with high-quality, custom flanges that meet all industry standards.